1. Field of the Invention
The invention relates to a mechanism for varying the opening of a valve actuated by a rocker arm and more specifically to deactivating selected cylinders of an Otto Cycle Engine with such a mechanism.
2. Description of the Prior Art
The concept of deactivating selected cylinders of an engine by disabling the valves associated with the selected cylinders is old. When this concept is applied to an Otto Cycle Engine, pumping or throttling losses are reduced, thereby improving engine efficiency during part throttle operation. Mechanisms proposed in the prior art to carry out the concept have had some disadvantages, e.g., they were either expensive, unreliable, required extensive engine modifications, could not be switched on or off during engine operation, or caused clashing of components in the valve drive train due to the mechanism either physically separating valve train components or reducing forces tending to keep connecting components in driving contact.